If light has no mass ....?

Question

(hence it can go 186,000 miles per second instantaneously without acceleration) then how can it provide a "push" for instance on solar sails in space. How can mere energy "push" or apply a physical force on matter?

Answer 1

Because a photon has a momentum but no rest mass. I know I was very confused by this too as a freshman physics student. According to classical physics this doesn't make sense.

According to relativity, you can only really measure the rest mass of an object when you are at rest with respect to the object in the case of a photon its rest mass is zero. When an object is moving relative to an observer it has kinetic energy and since energy and mass are related it can have a mass equivalent by virtue of having energy.

That is the best non-mathematical explanation I can give you.

Answer 2

Energy and matter(mass) are not as different as human intuition thinks. Remember E = MC^2
Energy (E) and mass (M) are intrinsically linked and can change from matter to energy and energy to matter, so any form of energy can have effects like momentum to provide a push.
Our description of how this works is called quantum mechanics. (this is where the world becomes very weird and way beyond my meager knowledge) Quantum mechanics does not allow energy like light to be divided up into smaller and smaller amounts because there is a minimum indivisible amount allowed. (This is similar to the ancient Greek idea of an atom of matter but about energy). When you look at the world at this scale there is no difference between particles and waves so what looks like light waves to us would at the minuscule level be a stream of particles that could push a solar sail while still acting like waves. This is called wave particle duality.

Answer 3

Unfortunatly there is not any sparkling explaination. First you're able to define mass. Does it have weight? the assumption of photons is that the take place basically whilst easy is modern, yet as quickly as the sunshine is off they disappear and have no information of ever present. - issues do no longer basically dissappear. If photons had mass they'd proceed to be after the sunshine grew to become into off - like water from a hose. in actuality there are some residences to easy that make certain the colour and brightness. that is like asserting does sound have mass? nicely air does, yet does sound? No that is vibrations for the time of the air. anyhow, i do no longer think of that is been shown the two way.